This invention relates to newly identified polynucleotides, polypeptides encoded by such polynucleotides, the use of such polynucleotides and polypeptides, as well as the production and isolation of such polynucleotides and polypeptides. More particularly, the polypeptide of the present invention has been identified as an amidase and in particular an enzyme having activity in the removal of arginine, phenylalanine or methionine from the N-terminal end of peptides in peptide or peptidomimetic synthesis.
Thermophilic bacteria have received considerable attention as sources of highly active and thermostable enzymes (Bronneomeier, K. and Staudenbauer, W. L., D. R. Woods (Ed.), The Clostridia and Biotechnology, Butterworth Publishers, Stoneham, Mass. (1993). Recently, the most extremely thermophilic organotrophic eubacteria presently known have been isolated and characterized. These bacteria, which belong to the genus Thermotoga, are fermentative microorganisms metabolizing a variety of carbohydrates (Huber, R. and Stetter, K. O., in Ballows, et al., (Ed.), The Procaryotes, 2nd Ed., Springer-Verlaz, N.Y., pgs. 3809-3819 (1992)).
Because to date most organisms identified from the archaeal domain are thermophiles or hyperthermophiles, archaeal bacteria are also considered a fertile source of thermophilic enzymes.
In accordance with one aspect of the present invention, there is provided a novel enzyme, as well as active fragments, analogs and derivatives thereof.
In accordance with another aspect of the present invention, there are provided isolated nucleic acid molecules encoding an enzyme of the present invention including mRNAs, DNAs, cDNAs, genomic DNAs as well as active analogs and fragments of such enzymes.
In accordance with yet a further aspect of the present invention, there is provided a process for producing such a polypeptide by recombinant techniques comprising culturing recombinant prokaryotic and/or eukaryotic host cells, containing a nucleic acid sequence encoding an enzyme of the present invention, under conditions promoting expression of said enzyme and subsequent recovery of said enzyme.
In accordance with yet a further aspect of the present invention, there is provided a process for utilizing such enzyme, or polynucleotide encoding such enzyme. The enzyme is useful for the removal of arginine, phenylalanine, or methionine amino acids from the N-terminal end of peptides in peptide or peptidomimetic synthesis. The enzyme is selective for the L, or "natural" enantiomer of the amino acid derivatives and is therefore useful for the production of optically active compounds. These reactions can be performed in the presence of the chemically more reactive ester functionality, a step which is very difficult to achieve with nonenzymatic methods. The enzyme is also able to tolerate high temperatures (at least 70.degree. C.), and high concentrations of organic solvents (&gt;40% DMSO), both of which cause a disruption of secondary structure in peptides; this enables cleavage of otherwise resistant bonds.
In accordance with yet a further aspect of the present invention, there is also provided nucleic acid probes comprising nucleic acid molecules of sufficient length to specifically hybridize to a nucleic acid sequence of the present invention.
In accordance with yet a further aspect of the present invention, there is provided a process for utilizing such enzymes, or polynucleotides encoding such enzymes, for in vitro purposes related to scientific research, for example, to generate probes for identifying similar sequences which might encode similar enzymes from other organisms.
These and other aspects of the present invention should be apparent to those skilled in the art from the teachings herein.
The following drawings are illustrative of embodiments of the invention and are not meant to limit the scope of the invention as encompassed by the claims.
FIG. 1 is an illustration of the full-length DNA and corresponding deduced amino acid sequence of the enzyme of the present invention. Sequencing was performed using a 378 automated DNA sequencer (Applied Biosystems, Inc.).
FIG. 2 shows the fluorescence versus concentration of DMSO. The filled and open boxes represent individual assays from Example 3.
FIG. 3 shows the relative initial linear rates (increase in fluorescence per min. i.e. "activity") versus concentration of DMF for the more reactive CBZ-L-arg-AMC, from